Speedfest (Team Echo)

Project Overview: 

Speedfest is a competition hosted by Oklahoma State University intended to foster enthusiasm for aviation and unmanned aircraft design. It challenges universities to design a remote controlled aerobatic trainer aircraft around the Kingtech K-45G Jet Turbine. Team Echo from Saint Louis University’s Parks College of Engineering, Aviation, and Technology is developed a straight trailing edge tapered wing aircraft in a canard configuration.The Speedfest Competition Statement of Work requires a trainer type aircraft that has a wingspan of less than 53”, capable of operating off of a 400 foot runway and achieve steady level flight speed of at least 100 knots; however, the aircraft must also be used as a sports/ aerobatic jet. These requirements drove the design of the aircraft to the canard configuration. Through airfoil selection, the canard was driven to stall before the wings of the aircraft, which in turn brings the nose of the aircraft down, making the aircraft difficult to stall for the training pilot. In addition, the g-forces experienced by the aircraft in the anticipated maneuvers required careful attention to the structural integrity of the aircraft. AEOLUS is a one of a kind aircraft fully built around the Kingtech K-45G jet turbine to allow pilots to train while being able to quickly switch to a fully aerobatic configuration.

Scoring:

Requirement Analysis:

The 2016 Speedfest challenged students to respond to a Statement of Work published on September 24, 2015:

    "There is a need for a remotely piloted (RP) sport jet that may also be used as a training aircraft for the new generation of small turbine engines. The aircraft developed under this  program will be a platform for pilots to safely train to receive their AMA Turbine Waiver, and then allow continued use as an aerobatic sport jet."

    As such, the aircraft should be safe easy for pilots transitioning to turbine aircraft, forgiving in handling qualities (both pre and post stall), robust, and simple to service, maintain, and operate. After demonstrations of all of the prototype aircraft, one will be chosen by a qualified team of judges selected from the  industry, government, academia, and experienced RP turbine operators. 

Along with the description, the SOW clearly states the requirements and constraints along with threshold and objective goals. The aircraft must be of novel design and be completely student built. The competition also requires students to host an exposition of their design to industry judges and spectators.

Mission Requirements:

Design Requirements:

All designs must satisfy all AMA requirements detailed in 510-a "Safety Regulations for Model Aircraft Powered by Gas Turbines." 

Mission profile of the competition is to take-off, fly as many figure 8 pylons as possible in 60 seconds. After flying the pylons, then the aircraft must perform an airshow consisting of at least Horizontal Figure-8's, Cuban 8's, Immelmann turn and reach its top speed.

Full rules and requirements are shown on the competition website here.

Propulsion System:

The biggest driving design requirement was using an unmodified KingTech K-45G turbine engine. The K-45G engine will start and run on diesel, kerosene and JetA1 fuels with a single fuel feed designed for a clean and simple engine installation. The package also includes a HP Tech ZP25M Fuel Pump, Xicoy ECU, System Analyzer, all leads and fuel tubing, manual fuel valve as well as a fuel filter with mounting clips. The K-45G model has a diameter of 3 inches and a length of 7.68 inches, standing at a total weight of 1.77 lbs when fully assembled. Based on Kintech specifications, the Max RPM of 162,000 is attainable producing 9.9 lbs of thrust at 15 degree Celsius temperature. The expected fuel consumption is measured to be 5.46 oz/min using either Diesel, Jet A1 or kerosene with 5% lubrication.

A dynamic test was set up for the engine to verify the performance specifications. It was mounted to drawer slides, which provided it with travel to apply tension. This system was then connected by a steel cable to a fish scale mounted at a safe standoff distance from the exhaust. First, the weight of the cables with the engine not running was noted. Then, the engine was ran at full throttle, and the reading of the fish scale recorded by video. The peak value seen was extracted from this video. Tanking this reading and the weight of the cable, the static thrust of the engine was found to be 10.3 pounds, running at peak RPMs of 168,000. These both showed about a 4% increase from manufacturer specifications. The test was run with and without the inlet, there was no difference in performance noticed.

Design:

Aeolus is designed with an interior inlet to streamline the design, keeping the drag at a minimum. The needed volume for sub-components, engine, inlet, fuel tanks and payload drove the size of the airframe. The body is 44’’ long with an oval cross-section of 6’’ in height, 7’’ in width. Using this configuration, the center of gravity lies exactly in the center of the fuel tank; meaning minimal c.g. and pitch moment shift during flight. The wingspan is 47 inches, below the design constraint of 53 inches, with an aspect ratio of 4.95 and a wing loading of 4.6 psf.

A numerical performance analysis was created to output the various forces, accelerations, distance traveled, and velocity of the aircraft in steady level flight (including canard deflections and angle of attack of the aircraft), beginning with a ground roll including rolling friction, through to in the air flight. The chosen wing and canard dimensions, combined with fuselage and component dimensions and weights, were input to this spreadsheet, and the performance evaluated. Following several iterations on the ground roll distance, acceleration performance, and other characteristics, the wing was eventually fixed at a 13 inch root, a 6 inch tip, and a total span of 47 inches. The takeoff distance was then verified from simplified analytic solutions

Since the aircraft needs to be highly maneuverable and able to perform precision aerobatics, the aircraft will experience high g-force loading. A flight envelope (or V-n diagram) was created based on the aircraft's current configuration as stated in the aerodynamics section. It shows the load factor curves plotted versus the velocity, including the gust lines. The velocity is in knots equivalent air speed, which is the same as true airspeed since there are no altitude effects. The positive limiting load factor is 15g and the negative load factor was around 13g. An important piece to note from the flight envelope is that the gust loads fall within the design parameters and the max velocity that can be achieved for level flight at max thrust is 130 knots, while 202 is max allowable dive speed. The stall speed was shown to be at 35 knots.

The fuselage is based on a semimonocoque structure. A semimonocoque structure is designed around an internal structural frame that consist of bulkheads and longerons. The bulkheads and longerons are made of plywood while the skin is made of a layer of carbon fiber and two layers of fiber glass. The wings are foam with a plywood spar and a balsa wood leading and trailing edge, wrapped in a layer of carbon fiber and two layers of fiber glass. The fiberglass was chosen as the outer edge so it could be sanded and painted easier. The inlet was 3D printed in the SLU Tinker Lab with P430 plastic material. It was designed as an external inlet and integrated so the front is over the leading edge of the wing and ends at the front of intake of the engine.

After all the manufacturing was finished, the final design stood ready for testing. 

Cost:

A large part of the scoring is the unit cost bid price. For this, Team Echo plans to build an economical aircraft that does not sacrifice quality. To do this, detained analysis must be done on each aspect of the design. This will insure only minor changes shall be needed once production of the first aircraft is complete. The current project, budgeted for fully building two aircraft as well as travel expenses, has a projected cost budget of $7,144.77. 23% of this cost is geared towards travel to the competition, 8% for material (balsa wood, epoxy, carbon fiber fabric and vacuum material) and 4% for tools. The largest portion of the funds will be aimed towards parts, 63% (engine, transmitter, receivers, gas tanks, retractable landing gear, servos, and wiring). The remaining 2% is set aside for miscellaneous items.

    Aeolus was fully funded thank to Saint Louis University as well as out sponsor Volpi co., SH Racing and Sponsorship Science.

Business Model:

The SOW states the design will be judged based on a cost projection of manufacturing 100 units to industry personnel. The target group are people already involved in the RC airplane hobby wanting to transition into the Jet engine aircraft world. The RC toy market was a $500 million market in 2014 with projection of growing over the next few years. Outside of the hobbyist market, there are potentials of meeting commercial and military needs with this aircraft. The military has geared toward UAV’s. It is only a matter of time before fighter UAV’s are developed. This design would be a great trainer UAV that would help pilots transition to more sophisticated designs. 

The aircraft will be priced based on an 100 unit manufacturing capacity. By buying in bulk, the total material/ labor cost per aircraft will be $2,700 with the ability to retail for $3,800. Aeolus is priced well below the cheapest competitor that has theirs retailed for $4,500. Aeolus is more practical and easier for use, as it would come 90% preassembled. The aircraft is also more structurally sound having been made out of composites rather than the competitor whose aircraft is fully foam with a balsa wood fuselage.

The model illustrates the start-up costs of manufacturing 100 Aeolus aircraft. This includes buying a 3-D printer, laser printer and all of the material and laber costs associated with each component. By retailing Aeolus for $3,800 we will be making a profit of a little less than 30%.

Conclusion:

Aeolus is a one of  a kind aircraft designed and constructed around the KingTech K-45G turbine engine for optimum performance. Aeolus is a trainer aircraft that is capable of full aerobatic maneuvers at the press of a button. With the unique canard configuration, Aeoluss’ canards stall before the wing; providing a pilot more time for recovery. Aeolus is designed to compete at the 2016 SpeedFest Competition hosted by Oklahoma State University.

Team Contact Information:

Nedret Ramic:  nramic4@slu.edu

           Team Lead, Propulsion Lead, Stability and Control

Enis Brdarevic: ebrdarev@slu.edu

           Structures Lead, Propulsion

Brandon Herges: bherges@slu.edu

           Aerodynamics Lead, Stability and Control Lead

Weston Mariottini: wmariott@slu.edu

           Systems Lead, Structures